The thermal chemistry of 1-chloro-3-iodopropane (ClC{sub 3}H{sub 6}I) adsorbed on Pt(111)

Journal Article · Thu Nov 04 04:00:00 EST 1999 · Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical

DOI:https://doi.org/10.1021/jp991923n· OSTI ID:20003203

Scoggins, T B; White, J M

This paper describes the thermally activated surface chemistry of 1-chloro-3-iodopropane, ClC{sub 3}H{sub 6}I, on Pt(111). The work is related to companion studies on other C{sub 3}adsorbates investigated in the laboratory, including cyclopropane, c-C{sub 3}H{sub 6}. HREELS and XPS indicate negligible dissociation of ClC{sub 3}H{sub 6}I during adsorption at 100 K. During TPD, no ClC{sub 3}H{sub 6}I desorbs for coverages below 0.4 ML. For higher, but not multilayer coverages, parent ClC{sub 3}H{sub 6}I desorption occurs in two peaks, 200 and 230 K. After even larger doses, unsaturable multilayer desorption occurs at 170 K. HREELS indicates that most C-I bonds dissociate by 205 K. The following reaction paths are proposed on the basis of TPD and HREELS results. When the C-I bond breaks, 3-chloropropyl fragments, C{sub (a)}H{sub 2}CH{sub 2}CH{sub 2}Cl, are formed and these either lose HCl to form {eta}{sup 3}- or {eta}{sup 1}-allyl or lose a {beta}-hydrogen to form 3-chloro-di-{sigma}-propylene. Some {eta}{sup 3}-allyl groups hydrogenate to either propylene, some of which desorbs at 240 K, or n-propyl, some of which hydrogenates to release propane at 250 K. Other {eta}{sup 3}-allyl groups isomerize to {eta}{sup 1}-allyl. At 250 K, 3-chloro-di-{sigma}-propylene eliminates chlorine as HCl and also releases H atoms that hydrogenate neighboring C{sub 3} fragments. The {eta}{sup 1}-allyl fragment either hydrogenates and desorbs as propylene at 325 K or isomerizes to propylidyne. Propyl and di-{sigma}-propylene moieties rearrange to form propylidyne or release propylene at 325 K. Interestingly, there is some benzene desorbing at 375 K. To account for it, a diene metallacycle is suggested. Atomic iodine desorbs at 825 K. Comparisons of the thermal chemistry of ClC{sub 3}H{sub 6}I on Ag(111) and Ni(100) are made as are comparisons of ClC{sub 3}H{sub 6}I with other C{sub 3} adsorbates on Pt(111).

• Research Organization: Univ. of Texas, Austin, TX (US)
• Sponsoring Organization: US Department of Energy; Robert A. Welch Foundation
• OSTI ID: 20003203
• Journal Information: Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical, Journal Name: Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical Journal Issue: 44 Vol. 103; ISSN JPCBFK
• Country of Publication: United States
• Language: English

Related Subjects

40 CHEMISTRY
CHLORINATED ALIPHATIC HYDROCARBONS
DISSOCIATION
IODINATED ALIPHATIC HYDROCARBONS
PLATINUM
SORPTIVE PROPERTIES
THERMOCHEMICAL PROCESSES